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Category Archives for "Networking"

Eliminate East-West Traffic Hair-Pinning

A firewall is a firewall, right? While on the surface that assumption may appear to be correcta closer look reveals that there are critical differences between a traditional, appliance-based firewall that protects your network perimeter and a distributedscale-out internal firewall that protects east-west traffic within your data center.  

It’s true that both types of firewalls monitor network traffic, detect threats, and block malicious activity. However, appliance-based firewalls are designed to monitor north-south traffic, which has different volumes and characteristics than east-west traffic. Traditional north-south firewalls were never designed to be used interchangeably to protect both north-south and east-west traffic 

East-West Data Center Traffic

Figure 1: Data center traffic patterns

While it might appear to be the right choice, provisioning appliance-based firewalls for east-west traffic monitoring is not only expensive, it’s highly ineffective in delivering the level of control and performance required to protect growing numbers of dynamic workloads.  

Creating Traffic Jams During Volume Spikes     

One of the most common drawbacks of using appliance-based firewalls as internal firewalls is the need to hairpin east-west traffic to and Continue reading

MPLS Applications/Services

MPLS Applications, what are the MPLS Applications?. MPLS Applications mean MPLS Services. So what can we do with MPLS basically.

Although the very first purpose of MPLS was fast switching, by the time services/applications with MPLS evolved and there are just so many reasons to use MPLS.

 

Below are some of the most common use case , or in other words, Applications with MPLS.

 

Important MPLS applications/services for the network designers are listed below.

 

    • Layer 2 MPLS VPN (EoMPLS, VPLS, EVPN , VXLAN EVPN etc.)
    • Layer 3 MPLS VPN
    • Inter-AS MPLS VPNs (Layer 2 or Layer 3)
    • Carrier Supporting Carrier
    • MPLS Traffic Engineering
    • Seamless MPLS
    • GMPLS (Generalized MPLS)
    • MPLS Transport Profile (MPLS-TP)

 

MPLS infrastructure can have all of the above MPLS application/ services at the same time. Most of them are architecture, so MPLS Labeling protocols itself (such as LDP, RSVP) are not enough for providing above applications/services.

Usually MPLS protocols, are used commonly with BGP, IGP and other protocols.

I just wanted to mention what people mean when they talk about MPLS applications, thus I am keeping post short but before I finish the post, let me recommend you a book, called . ‘ MPLS Continue reading

Integrated Services QoS – Hard QoS

Integrated Services QoS – Hard QoS is first QoS approach, but currently we are not using. At the end of this post, you will know what is Integrated QoS, what was the idea with it and why it is not used today.

 

Quality of service (QoS) is the overall performance of a telephony or computer network, particularly the performance seen by the users of the network.

Two QoS approaches have been defined by standard organizations.

These are:

  • Intserv (Integrated Services) and
  • Diffserv (Differentiated Services).

Intserv QoS demands that every flow requests a bandwidth from the network and that the network would reserve the required bandwidth for the user during a conversation.

Think of this as on-demand circuit switching, each flow of each user would be remembered by the network. This clearly would create a resource problem (CPU, memory , bandwidth) on the network, and thus it was never widely adopted.

Not only allocation bandwidth for each and every flow on each network device in the path, but also keep tracking these flows and tearing down when the flow is terminated is very resource intensive and people thought this will not be scalable and we haven’t seen deployment for it.

Protocol Continue reading

Some must to know information about VPNs

VPN – Virtual Private Network is most common overlay mechanism in Networking. We have many of them, GRE, mGRE, IPSEC, DMVPN, GETVPN, LISP, FlexVPNs, MPLS VPNs and so on. But what are the important and fundamentals thing about VPNs?.In this post I will explain some of them.

 

Virtual Private Network is the logical entity, which is created over a physical infrastructure. It can be setup over another private network such as MPLS or public network such as Internet.

 

All VPN technologies add extra byte to the packet or frame, which increases the overall MTU so the network links should be accommodated to handle bigger MTU values.

 

VPN technologies work based on encapsulation and decapsulation.

 

For example GRE, mGRE and DMVPN encapsulate IP packets into another IP packet, VPLS and EVPN encapsulates Layer 2 frame into an MPLS packets.

 

You can run routing protocols over some VPN technologies but not all VPN technologies allow you to run routing protocols.

In order to support routing over tunnel, tunnel endpoints should be aware from each other.

 

For example MPLS Traffic Engineer tunnels don’t support routing protocols to run over, since the LSPs are unidirectional which mean Head-end Continue reading

OPEX and CAPEX in Network Design

OPEX and CAPEX are two important network design considerations. From the high level we should understand these two design requirements.

 

OpEx refers to operational expenses such as support, maintenance, labor, bandwidth and utilities. Creating a complex network design may show off your technical knowledge but it can also cause unnecessary complexity making it harder to build, maintain, operate and manage the network.

 

A well- designed network reduces OpEx through improved network uptime (which in turn can avoid or reduce penalties related to outages), higher user productivity, ease of operations, and energy savings. Consider creating the simplest solution that meets the business requirements.

 

CapEx refers to the upfront costs such as purchasing equipment, inventory, acquiring intellectual property or real estate. A well-thought design provides longer deployment lifespan, investment protection, network consolidation and virtualization, producing non-measurable benefits such as business agility and business transformation and innovation, thus reducing risk and lowering costs in the long run.

 

Last metric in the COST constraint is TCO (Total cost of ownership).

TCO is a better metric than pure CapEx to evaluate network cost, as it considers CapEx plus OpEx. Make your network designs cost-effective in the long run and do more Continue reading

BGP Path Validation New Mechanism – AS Cones

When it comes to Routing Security, BGP Origin and Path Validation should be understood very well.

It is the problem of all, not just large Service Providers. Enterprises, Service Providers, Mobile Operators, basically whoever are interacting with Global Routing.

IRR, RPKI, BGPSEC, Origin Validation and Path Validation are the fundamentals of BGP Routing Security. We have many other posts for the subject on the website but in this post I want to share with you new approach for BGP Path Validation. It is called as AS-Cones.

At the moment, it is still IETF draft but soon it is expected to be Standard RFC.

I discussed it with the inventor of the mechanisms, Melchior Aelmans along with many other routing security topic and decided to share with you!

In the below video, Orhan Ergun, Melchior Aelmans and Jeff Tantsura, discussing new approaches in BGP Security – Path Validation.

They explain ASPA – Autonomous System Provider Authorization , and another approach AS-Cone and they compare those two.

Not only BGP Security Path Validation, but they identify the current known problems of the Global Routing Table/DFZ, such as Hijacks, different types of hijacks, route leaks and they discuss some prevention techniques such Continue reading

Flat/Single Level vs. Multi Level IS-IS Design Comparison

Flat/Single Level vs. Multi Level IS-IS Design Comparison. Flat routing means, without hierarchy, entire topology information of the network is known by each and every device in the network.

IS-IS has two levels. Thus, for IS-IS, Multi Level means Two Level IS-IS. Level 1 and Level 2.

When we have two levels, Level 1 routers don’t know the topology of Level 2 and vice versa. By hiding topology information of different level routers, scalability is achieved. Reason we achieve more scalable network is when there is a failure or new information added or metric changes in one Level, another level doesn’t run SPF algorithm.

 

But what are the design consideration when we have Flat or Multi Level IS-IS networks. Is Multi Level IS-IS design, which mean, Hierarchical IS-IS design always good? Answer is no. Although Multi Level provides Scalability, it comes with extra complexity and end to end routing convergence time increase.

 

So, I prepared below comparison charts to discuss different design aspects when it comes to IS-IS Single vs. Multi Level design.

 

If you like this comparison chart, you can see more of them in my CCIE Enterprise Training.

 

single vs. multi level IS-IS

The post Flat/Single Level vs. Multi Continue reading

Four necessary steps in routing fast convergence

When it comes to fast convergence, first thing that we need to understand what is convergence?

 

Convergence is the time between failure and the recovery. Link, circuits, routers, switches all eventually fails. As a network designers, our job is to understand the topology and whenever there is qrequirement, add backup link or node. Of course, not every network, or not every place in the network requires redundancy though. But let’s assume, we want redundancy, thus we add backup link or node and we want to recover from the failure as quickly as possible, by hoping before Application timeout.

 

But what is the time for us to say , this network is converging fast. Unfortunately, there is no numerical value for it. So, you cannot say, 30 seconds , or 10 seconds , or 1 second is fast convergence. Your application convergence requirement might be much below 1 second.

Thus, I generally call ‘ Fast Convergence’ is the convergence time faster than default convergence value. Let’s say, OSPF on Broadcast media is converging in 50 seconds, so any attempt to make OSPF convergence faster than 50 seconds default convergence value is OSPF Fast Convergence on Broadcast media.

 

There Continue reading

What is MTL in CCIE Enterprise Infrastructure Training?

MTL – Multi Technology Lab consist of many technologies in a large topology. When network design is considered, there is no single protocol, many protocols interact with each other. In my CCIE Enterprise Infrastructure Training, I have many MTL (Multi Technology Lab), and students are able to watch the videos, and with the config files, they are able to perform each task in the Lab themselves.

 

From OSPF, EIGRP to BGP, QoS to Multicast, Layer 2 Technologies to Security, SD-WAN and many other technologies are all in the same lab. Traditionaly these kind of Labs were called as Mock Labs but better term is Multi Technology Lab. If you see on the social media next time one of this labs with OE logo, you know that it is MTL! Let me see your comment 🙂

 

You can check the schedule of next CCIE Enterprise Course by clicking here! 

Multi Technology Lab

The post What is MTL in CCIE Enterprise Infrastructure Training? appeared first on orhanergun.net.

OSPF Routing Protocol Network Engineer Interview Questions!

OSPF is the most common network engineer interview topics without any doubt. Almost all network engineers faced with some OSPF questions in their interview. Thus I thought it is important to cover common questions and the answer with the blog post.

 

From OSPF LSAs to OSPF Areas, by having Multi Area Hierarchical OSPF for stability, OSPF security and OSPF Fast Convergence, I prepared many questions and explaining them in detail in the below video.

 

There are many questions in the video and if you liked the video, subscribe to Orhan Ergun YouTube Channel and share your thoughts in the comment section.

 

Note: OSPF Interview Questions in this video from basics to advanced level and studying this 65 minutes video will enhance your OSPF knowledge definitely!

 

The post OSPF Routing Protocol Network Engineer Interview Questions! appeared first on orhanergun.net.

Introducing Contour: Routing Traffic to Applications in Kubernetes

KubeCon + CloudNativeCon and VMware sponsored this post, in anticipation of the virtual an incubation-level hosted project with the Cloud Native Computing Foundation (CNCF). This is a very proud moment and on behalf of the other project maintainers we want to thank the community for all of the work they put in to get us to this point. If you don’t already know it, Contour is a simple and scalable open source ingress controller for routing traffic to applications running in Kubernetes. We’ll be offering an in-depth look at how Contour works and outlining our development roadmap at a 

Appreciation Society

Given how crazy everything is right now, it’s important to try and stay sane. And that’s harder than it sounds to be honest. Our mental health is being degraded by the day. Work stress, personal stress, and family stress are all contributing to a huge amount of problems for all of us. I can freely admit that I’m there myself. My mental state has been challenged as of late with a lot of things and I’m hoping that I’m going to pull myself out of this funk soon with the help of my wife @MrsNetwrkngnerd and some other things to make me happier.

One of the things that I wanted to share with you all today was one of the things I’ve been trying to be mindful about over the course of the last few months. It’s about appreciation. We show appreciation all the time for people. It’s nothing new, really. But I want you to think about the last time you said “thank you” to someone. Was it a simple exchange for a service? Was it just a reflex to some action? Kind of like saying “you’re welcome” afterwards? I’d be willing to bet that most of the people Continue reading

Heavy Networking 533: Packet Pushers Roundtable – SD-Branch, BGP Over QUIC, Bandwidth Avoidance

Today's episode assembles the Packet Pushers to wrangle over a grab bag of ideas including the evolution from SD-WAN to SD-Branch, new compression standards to preserve Internet bandwidth, and the pros and cons of BGP over QUIC.

The post Heavy Networking 533: Packet Pushers Roundtable – SD-Branch, BGP Over QUIC, Bandwidth Avoidance appeared first on Packet Pushers.

Microsoft uses AI to boost its reuse, recycling of server parts

Microsoft is bringing artificial intelligence to the task of sorting through millions of servers to determine what can be recycled and where.The new initiative calls for the building of so-called Circular Centers at Microsoft data centers around the world, where AI algorithms will be used to sort through parts from decommissioned servers or other hardware and figure out which parts can be reused on the campus. READ MORE: How to decommission a data center Microsoft says it has more than three million servers and related hardware in its data centers, and that a server's average lifespan is about five years. Plus, Microsoft is expanding globally, so its server numbers should increase.To read this article in full, please click here

Protecting Remote Desktops at Scale with Cloudflare Access

Protecting Remote Desktops at Scale with Cloudflare Access

Early last year, before any of us knew that so many people would be working remotely in 2020, we announced that Cloudflare Access, Cloudflare’s Zero Trust authentication solution, would begin protecting the Remote Desktop Protocol (RDP). To protect RDP, customers would deploy Argo Tunnel to create an encrypted connection between their RDP server and our edge - effectively locking down RDP resources from the public Internet. Once locked down with Tunnel, customers could use Cloudflare Access to create identity-driven rules enforcing who could login to their resources.

Setting Tunnel up initially required installing the Cloudflare daemon, cloudflared, on each RDP server. However, as the adoption of remote work increased we learned that installing and provisioning a new daemon on every server in a network was a tall order for customers managing large fleets of servers.

What should have been a simple, elegant VPN replacement became a deployment headache. As organizations helped tens of thousands of users switch to remote work, no one had the bandwidth to deploy tens of thousands of daemons.

Message received: today we are announcing Argo Tunnel RDP Bastion mode, a simpler way to protect RDP connections at scale. 🎉 By functioning as a Continue reading

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